The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_clock.c

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    1 /*-
    2  * Copyright (c) 1988 University of Utah.
    3  * Copyright (c) 1982, 1990, 1993
    4  *      The Regents of the University of California.  All rights reserved.
    5  *
    6  * This code is derived from software contributed to Berkeley by
    7  * the Systems Programming Group of the University of Utah Computer
    8  * Science Department.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 4. Neither the name of the University nor the names of its contributors
   19  *    may be used to endorse or promote products derived from this software
   20  *    without specific prior written permission.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  *
   34  *      from: Utah $Hdr: clock.c 1.18 91/01/21$
   35  *      from: @(#)clock.c       8.2 (Berkeley) 1/12/94
   36  *      from: NetBSD: clock_subr.c,v 1.6 2001/07/07 17:04:02 thorpej Exp
   37  *      and
   38  *      from: src/sys/i386/isa/clock.c,v 1.176 2001/09/04
   39  */
   40 
   41 /*
   42  * Helpers for time-of-day clocks. This is useful for architectures that need
   43  * support multiple models of such clocks, and generally serves to make the
   44  * code more machine-independent.
   45  * If the clock in question can also be used as a time counter, the driver
   46  * needs to initiate this.
   47  * This code is not yet used by all architectures.
   48  */
   49 
   50 /*
   51  * Generic routines to convert between a POSIX date
   52  * (seconds since 1/1/1970) and yr/mo/day/hr/min/sec
   53  * Derived from NetBSD arch/hp300/hp300/clock.c
   54  */
   55 
   56 #include <sys/cdefs.h>
   57 __FBSDID("$FreeBSD: releng/6.4/sys/kern/subr_clock.c 139804 2005-01-06 23:35:40Z imp $");
   58 
   59 #include <sys/param.h>
   60 #include <sys/systm.h>
   61 #include <sys/kernel.h>
   62 #include <sys/bus.h>
   63 #include <sys/clock.h>
   64 #include <sys/sysctl.h>
   65 #include <sys/timetc.h>
   66 
   67 /* XXX: for the  CPU_* sysctl OID constants. */
   68 #include <machine/cpu.h>
   69 
   70 #include "clock_if.h"
   71 
   72 static __inline int leapyear(int year);
   73 static int sysctl_machdep_adjkerntz(SYSCTL_HANDLER_ARGS);
   74 
   75 #define FEBRUARY        2
   76 #define days_in_year(y)         (leapyear(y) ? 366 : 365)
   77 #define days_in_month(y, m) \
   78         (month_days[(m) - 1] + (m == FEBRUARY ? leapyear(y) : 0))
   79 /* Day of week. Days are counted from 1/1/1970, which was a Thursday */
   80 #define day_of_week(days)       (((days) + 4) % 7)
   81 
   82 static const int month_days[12] = {
   83         31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
   84 };
   85 
   86 static device_t clock_dev = NULL;
   87 static long clock_res;
   88 
   89 int adjkerntz;          /* local offset from GMT in seconds */
   90 int disable_rtc_set;    /* disable resettodr() if != 0 */
   91 int wall_cmos_clock;    /* wall CMOS clock assumed if != 0 */
   92 
   93 /*
   94  * These have traditionally been in machdep, but should probably be moved to
   95  * kern.
   96  */
   97 SYSCTL_PROC(_machdep, CPU_ADJKERNTZ, adjkerntz, CTLTYPE_INT|CTLFLAG_RW,
   98         &adjkerntz, 0, sysctl_machdep_adjkerntz, "I", "");
   99 
  100 SYSCTL_INT(_machdep, CPU_DISRTCSET, disable_rtc_set,
  101         CTLFLAG_RW, &disable_rtc_set, 0, "");
  102 
  103 SYSCTL_INT(_machdep, CPU_WALLCLOCK, wall_cmos_clock,
  104         CTLFLAG_RW, &wall_cmos_clock, 0, "");
  105 
  106 static int
  107 sysctl_machdep_adjkerntz(SYSCTL_HANDLER_ARGS)
  108 {
  109         int error;
  110         error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2,
  111                 req);
  112         if (!error && req->newptr)
  113                 resettodr();
  114         return (error);
  115 }
  116 
  117 /*
  118  * This inline avoids some unnecessary modulo operations
  119  * as compared with the usual macro:
  120  *   ( ((year % 4) == 0 &&
  121  *      (year % 100) != 0) ||
  122  *     ((year % 400) == 0) )
  123  * It is otherwise equivalent.
  124  */
  125 static __inline int
  126 leapyear(int year)
  127 {
  128         int rv = 0;
  129 
  130         if ((year & 3) == 0) {
  131                 rv = 1;
  132                 if ((year % 100) == 0) {
  133                         rv = 0;
  134                         if ((year % 400) == 0)
  135                                 rv = 1;
  136                 }
  137         }
  138         return (rv);
  139 }
  140 
  141 int
  142 clock_ct_to_ts(struct clocktime *ct, struct timespec *ts)
  143 {
  144         time_t secs;
  145         int i, year, days;
  146 
  147         year = ct->year;
  148 
  149         /* Sanity checks. */
  150         if (ct->mon < 1 || ct->mon > 12 || ct->day < 1 ||
  151             ct->day > days_in_month(year, ct->mon) ||
  152             ct->hour > 23 ||  ct->min > 59 || ct->sec > 59 ||
  153             ct->year > 2037)            /* time_t overflow */
  154                 return (EINVAL);
  155 
  156         /*
  157          * Compute days since start of time
  158          * First from years, then from months.
  159          */
  160         days = 0;
  161         for (i = POSIX_BASE_YEAR; i < year; i++)
  162                 days += days_in_year(i);
  163 
  164         /* Months */
  165         for (i = 1; i < ct->mon; i++)
  166                 days += days_in_month(year, i);
  167         days += (ct->day - 1);
  168 
  169         /* Another sanity check. */
  170         if (ct->dow != -1 && ct->dow != day_of_week(days))
  171                 return (EINVAL);
  172 
  173         /* Add hours, minutes, seconds. */
  174         secs = ((days * 24 + ct->hour) * 60 + ct->min) * 60 + ct->sec;
  175 
  176         ts->tv_sec = secs;
  177         ts->tv_nsec = ct->nsec;
  178         return (0);
  179 }
  180 
  181 void
  182 clock_ts_to_ct(struct timespec *ts, struct clocktime *ct)
  183 {
  184         int i, year, days;
  185         time_t rsec;    /* remainder seconds */
  186         time_t secs;
  187 
  188         secs = ts->tv_sec;
  189         days = secs / SECDAY;
  190         rsec = secs % SECDAY;
  191 
  192         ct->dow = day_of_week(days);
  193 
  194         /* Subtract out whole years, counting them in i. */
  195         for (year = POSIX_BASE_YEAR; days >= days_in_year(year); year++)
  196                 days -= days_in_year(year);
  197         ct->year = year;
  198 
  199         /* Subtract out whole months, counting them in i. */
  200         for (i = 1; days >= days_in_month(year, i); i++)
  201                 days -= days_in_month(year, i);
  202         ct->mon = i;
  203 
  204         /* Days are what is left over (+1) from all that. */
  205         ct->day = days + 1;
  206 
  207         /* Hours, minutes, seconds are easy */
  208         ct->hour = rsec / 3600;
  209         rsec = rsec % 3600;
  210         ct->min  = rsec / 60;
  211         rsec = rsec % 60;
  212         ct->sec  = rsec;
  213         ct->nsec = ts->tv_nsec;
  214 }
  215 
  216 void
  217 clock_register(device_t dev, long res)
  218 {
  219 
  220         if (clock_dev != NULL) {
  221                 if (clock_res > res) {
  222                         if (bootverbose) {
  223                                 device_printf(dev, "not installed as "
  224                                     "time-of-day clock: clock %s has higher "
  225                                     "resolution\n", device_get_name(clock_dev));
  226                         }
  227                         return;
  228                 } else {
  229                         if (bootverbose) {
  230                                 device_printf(clock_dev, "removed as "
  231                                     "time-of-day clock: clock %s has higher "
  232                                     "resolution\n", device_get_name(dev));
  233                         }
  234                 }
  235         }
  236         clock_dev = dev;
  237         clock_res = res;
  238         if (bootverbose) {
  239                 device_printf(dev, "registered as a time-of-day clock "
  240                     "(resolution %ldus)\n", res);
  241         }
  242 }
  243 
  244 /*
  245  * inittodr and settodr derived from the i386 versions written
  246  * by Christoph Robitschko <chmr@edvz.tu-graz.ac.at>,  reintroduced and
  247  * updated by Chris Stenton <chris@gnome.co.uk> 8/10/94
  248  */
  249 
  250 /*
  251  * Initialize the time of day register, based on the time base which is, e.g.
  252  * from a filesystem.
  253  */
  254 void
  255 inittodr(time_t base)
  256 {
  257         struct timespec diff, ref, ts;
  258         int error;
  259 
  260         if (base) {
  261                 ref.tv_sec = base;
  262                 ref.tv_nsec = 0;
  263                 tc_setclock(&ref);
  264         }
  265 
  266         if (clock_dev == NULL) {
  267                 printf("warning: no time-of-day clock registered, system time "
  268                     "will not be set accurately\n");
  269                 return;
  270         }
  271         error = CLOCK_GETTIME(clock_dev, &ts);
  272         if (error != 0 && error != EINVAL) {
  273                 printf("warning: clock_gettime failed (%d), the system time "
  274                     "will not be set accurately\n", error);
  275                 return;
  276         }
  277         if (error == EINVAL || ts.tv_sec < 0) {
  278                 printf("Invalid time in real time clock.\n");
  279                 printf("Check and reset the date immediately!\n");
  280         }
  281 
  282         ts.tv_sec += tz_minuteswest * 60 +
  283             (wall_cmos_clock ? adjkerntz : 0);
  284 
  285         if (timespeccmp(&ref, &ts, >)) {
  286                 diff = ref;
  287                 timespecsub(&ref, &ts);
  288         } else {
  289                 diff = ts;
  290                 timespecsub(&diff, &ref);
  291         }
  292         if (ts.tv_sec >= 2) {
  293                 /* badly off, adjust it */
  294                 tc_setclock(&ts);
  295         }
  296 }
  297 
  298 /*
  299  * Write system time back to RTC
  300  */
  301 void
  302 resettodr()
  303 {
  304         struct timespec ts;
  305         int error;
  306 
  307         if (disable_rtc_set || clock_dev == NULL)
  308                 return;
  309 
  310         getnanotime(&ts);
  311         ts.tv_sec -= tz_minuteswest * 60 + (wall_cmos_clock ? adjkerntz : 0);
  312         if ((error = CLOCK_SETTIME(clock_dev, &ts)) != 0) {
  313                 printf("warning: clock_settime failed (%d), time-of-day clock "
  314                     "not adjusted to system time\n", error);
  315                 return;
  316         }
  317 }

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